The present invention relates to methods, systems, and computer program products for estimating fetal weight at birth and risk of macrosomia. More particularly, the present invention relates to methods, systems, and computer program products for estimating fetal weight at birth and risk of macrosomia using a hierarchy of equations based on maternal characteristics and fetal ultrasound measurements.
Obstetricians have been searching for a method to successfully predict birth weight for hundreds of years. This motivation arises because fetuses with both low and high birth weights are at increased risk for newborn complications during the intrapartum and postnatal periods. The complications associated with the delivery of excessively large fetuses include prolonged labor, shoulder dystocia, brachial plexus injury, bony injuries, and intrapartum asphyxia, as well as maternal risks of birth canal and pelvic floor injuries and postpartum hemorrhage. In addition, the occurrence of cephalopelvic disproportion is more prevalent as fetal size increases, contributing to both an increased rate of operative vaginal delivery and of cesarean section for macrosomic fetuses as compared with fetuses of normal weight. Thus, there is an increase not only in the morbidity and mortality associated with the birth of macrosomic fetuses, but also a significant increase in both the direct and indirect costs associated with their birth and lifetime care.
If fetal weight could be known with reasonable certainty in advance of delivery, the timing and mode of delivery for women carrying macrosomic fetuses could be modified to improve newborn and maternal outcomes. The problem, until now, has been appropriately identifying abnormally grown fetuses in utero, so that modifications to the patient""s treatment and delivery plan could be instituted in advance of labor. Because of this, there is significant clinical utility to having a readily available tool to reliably estimate fetal weight before delivery.
Several approaches to prospective birth weight prediction have been attempted. For centuries, simply xe2x80x9cfeelingxe2x80x9d the size of a fetus through the maternal abdominal and uterine walls was the only tool that was available. The predictive accuracy of such tactile assessment of fetal size is suboptimal, with its overall accuracy ranging from xc2x17.5-19.8% of actual birth weight. During the past quarter century, this technique has gradually been supplanted by the method of ultrasonographic fetal biometry. The assumption underlying this change has been that fetal biometric assessments would yield superior estimates of birth weight because the multiple fetal measurements obtained via sonography are quantitative in nature and less xe2x80x9csubjectivexe2x80x9d than the information obtained by clinical means. This assumption presupposes that the sonographic measurements of multiple linear and planar dimensions of the fetus provide sufficient parametric information to allow for accurate algorithmic reconstruction of the three-dimensional fetal volume of varying tissue density. Consistent with these beliefs, much effort has been expended to generate best-fit fetal biometric algorithms that can make birth weight predictions based on obstetrical sonographic measurements alone. As such, the ultrasonographic technique represents the newest and most technologically sophisticated method of making fetal weight estimations. Although obstetrical ultrasonography has proven to be a boon as a tool to detect fetal anomalies, position, amniotic fluid volume and placental location, standard sonographic fetal biometric modeling has been an unfortunate failure with regard to predicting fetal weight. Its predictive accuracy has ranged from xc2x110.7%-15.6% of actual term birth weight, and it has never approached the level of accuracy required to make the method useful for making clinical decisions regarding optimal patient management.
Accordingly, there exists a need for improved methods and systems for estimating fetal weight at birth and risk of fetal macrosomia.
The present invention includes improved methods and systems for estimating fetal weight at birth and risk of macrosomia. The present invention may be implemented as a computer program that obtains information from a user and automatically estimates fetal birth weight and/or risk of macrosomia based on information provided by the user. As used herein, the term xe2x80x9cmacrosomiaxe2x80x9d refers to the condition of a fetus being born with a weight at birth that is greater than a predetermined value. The predetermined value may be based on accepted medical definitions and is preferably programmable by the user. The information used to estimate fetal weight and/or risk of macrosomia includes information regarding maternal characteristics and fetal ultrasound measurements. A user is presented with a questionnaire requesting information regarding maternal characteristics and fetal ultrasound measurements. The responses are input into fetal birth weight/macrosomia risk estimation software. The software runs through a series of logical steps that calculates fetal weight and/or risk of macrosomia based on the available information. More particularly, the software selects the most accurate equation from a uniquely devised set of equations that are empirically derived using statistical methods and multiple sets of proprietary data based on available information about the mother and/or fetal ultrasound measurements. The fetal birth weight/macrosomia risk estimation software outputs one or more numbers indicative of estimated fetal birth weight, risk of macrosomia, and confidence intervals associated therewith. Because the present invention calculates fetal weight at birth and risk of macrosomia by selecting the most accurate prediction equation for the available information, increased accuracy in predicting fetal weight at birth and risk of macrosomia is achieved. In addition, because the present invention allows for the calculation of fetal weight at birth and/or risk of macrosomia up to three months before the actual date of delivery, it allows both mothers and obstetrical practitioners time and flexibility in planning the timing and mode of delivery, so as to minimize the ultimate size of fetuses that are projected to be overgrown at particular junctures of gestation, and to minimize the risks of adverse outcomes associated with the delivery process for both these fetuses that are destined to be overgrown and their mothers. As a result, fetal injuries and injuries to the mother can be reduced.
Accordingly, it is an object of the invention to provide improved methods and systems for estimating fetal birth weight.
It is yet another object of the invention to provide improved methods and systems for estimating risk of fetal macrosomia.